1. Field of the Invention
The present invention relates to a so-called projector-type vehicular illumination lamp, and, in particular, to a vehicular illumination lamp including a light-emitting element serving as a light source.
2. Related Art
In recent years, light-emitting elements such as light-emitting diodes have been put into use as light sources for vehicular illumination lamps.
For example, “Patent Document 1” describes a projector-type vehicular illumination lamp including a projection lens disposed on an optical axis extending in a vehicular longitudinal direction, a light-emitting element disposed rearwardly of a rear-side focal point of the projection lens to be directed upward, and a main reflector disposed to cover the light-emitting element from an upper side to reflect light from the light-emitting element toward the projection lens.
In the vehicular illumination lamp described in “Patent Document 1,” a mirror member having an upward reflective surface extending rearward in parallel with the optical axis from the proximity of the rear-side focal point of the projection lens is provided between the main reflector and the projection lens, so that part of the reflected light from the main reflector is reflected upward by the mirror member to be incident on the projection lens and emitted forward via the projection lens. Consequently, a cut-off line of a low-beam light distribution pattern is formed as an inverted projection image of the front end edge of the upward reflective surface of the mirror member.
Meanwhile, “Patent Document 2” describes a projector-type vehicular illumination lamp in which first and second sub reflectors are disposed between a main reflector and a shade. In the vehicular illumination lamp described in “Patent Document 2,” light from a light source is reflected downward by the first sub reflector disposed above an optical axis and forwardly of the main reflector and then reflected by the second sub reflector disposed below the optical axis so that the reflected light is incident on a projection lens.
[Patent Document 1] Japanese Patent Application Laid-Open (Kokai) No. 2005-166590
[Patent Document 2] Japanese Patent Application Laid-Open (Kokai) No. 2007-329068